At the present time the most economic, technically viable method used for launching and accelerating high-mass space vehicles from the earth's surface to orbital or escape velocities is based upon rocket or jet propulsion wherein propulsive thrust is achieved by burning a gas inside pressure chambers and creating pressure differentials on the walls by expelling the gas through a system of nozzles. Unfortunately, since the required velocities are relatively high, most of the chemical energy is wasted accelerating large amounts of unburned fuel, and the inert structural mass required to contain it. Thus, the useful payload is a small fraction of the vehicle's initial launch mass. This has serious technical implications in terms of payload limitations which appear to be unavoidable.
The minimum mass ratio (launch mass/burn-out mass) for achieving low earth orbit using LH.sub.2 /LO.sub.2 propellant is about 10.0. Unfortunately, since the density of LH.sub.2 is very low, the vehicle must be designed with a large structural mass to contain it. Consequently, the required initial mass will be very high, even for relatively small payloads. Thus, the cost to put payloads into orbit is very-high even if the vehicle is reusable. For example, the expected minimum cost of transporting payloads into orbit by the proposed reusable single-stage Aerospace Plane propelled by idealized scramjets operating at maximum efficiency or by the vertically launched Delta Clipper will be about $300/kg ($136/lb), and the size and weight of the payloads will be relatively small.
The problem of achieving economical space travel does not involve energy. A long-range 747 airliner burns the equivalent of twice its own orbital energy in the fuel it consumes. The problem is the high mass ratio of the launch vehicle set by the rocket equation. Therefore, if the underlying propulsion principles (i.e., the technical methods) of space travel remain unchanged, space travel will always remain very expensive and way beyond the reach of ordinary citizens. The situation can not be significantly improved by utilizing remotely generated laser or microwave beams to heat the propellant gas because of thermal and structural limitations. Although nuclear propelled vehicles could achieve high velocities in interplanetary space, they could not be operated directly from the earth's surface. The basic mass ratio problem of launching payloads from the earth's surface into orbit would still remain.
The technical problem of achieving economical space travel is one of the most challenging problems in applied physics. In actually, the problem is not actively pursued because it is viewed as having no viable solution that is attainable with current technology. The propulsion method and operating system introduced herein will provide a solution to this problem. What is most significant is that this method is well within technological feasibility, and, from an engineering point of view, will be relatively easy to develop and implement. It could also be utilized as a propulsion method for achieving low-cost high-speed intercontinental transportation at speeds far beyond that of supersonic airliners.